1. Field of the Invention
This invention relates to an underfloor access housing providing access to a plurality of electrical services at one location in a building floor, and more particularly to improved means for positively connecting the housing to a cellular flooring unit.
2. Description of the Prior Art
Floor constructions are known comprising a metal subfloor supporting an overlying layer of concrete. The metal subfloor includes metal cellular flooring units providing generally parallel enclosed cells or raceways. Sets of access holes, usually prepunched at the factory, are provided for gaining access to the wiring extending through the raceways or cells of the metal cellular flooring unit. A preset access housing is installed over each set of access holes. The concrete is then poured over the metal subfloor and the housings. Initially, only a small number of the housings may actually be used. However, since the number and location of housings may vary substantially over the life span of the building, housings are provided throughout the floor area.
The access housings have been secured to the metal cellular flooring units by spot welding, see for example U.S. Pat. No. 3,592,956 (Fork) and by riveting and like fastening operations, all of which are time consuming operations requiring skilled personnel and special equipment.
Other fastening arrangements have been devised to facilitate attachment of the housing to the flooring unit. For example, resilient clips have been employed, having one end captively retained in the slot provided in the crest of a cell and an opposite end frictionally engaged over the access unit. The resilient clip also has been used in combination with a tab projecting from the housing downwardly into a slot in the crest of the cell. See, for example, U. S. Re. Pat. No. 28,035 (FORK). The use of extrinsic clips adds to the cost of the housing and to the time required to install the same.
In another arrangement, a rupturable block spans across the crests of adjacent cells and covers access openings formed in the crests. A hold-down plate holds the block in position. The hold-down plate is secured to the crests by tabs which extend outwardly from end walls of the plate and which are received in preformed slots in the crests of the adjacent cells. See U.S. Pat. No. 3,973,366 (BALANE et al). This arrangement does not utilize an access housing--the plate serving primarily to hold the block in position. Instead, a void or cavity remains in the concrete when the block is removed, for access to the cells and to the wiring carried thereby.